Need ideas for a tree house ladder

My yard has the most amazing tree. It's girth is anout 14 feet around the trunk. It's a fabulous old tree and we want to build a tree house in it. No problems with that part, but we can't figure out how to build the ladder to get up into the tree without damaging the tree.

Depending on how old the kids are, a rope ladder would work great. It's just a matter of wether or not the kids are old enough to manage it safely!
You can purchase traditional rope ladders, or make your own. If you make your own, you can just take a thick rope and knot it at intervals going up for the kids to put their feet on as the "rope climb" up it.

And the cool thing about a rope ladder is that they can pull it up while they are in the tree house if they don't want "intruders" .

I would use a rope ladder too, but I would use two ropes, with 2x6 pieces of wood about 18 inches long to make it more of a ladder. ust drill holes on both ends of the boards, and thread the ropes and tie large nots so the boards cannot slip. Space the boards no more then 10 to 12 inches apart (depending on the age of your children). It will be more like a ladder, with the flexibility of the rope and you can attach it to the actual house, not the tree. Not to mention, it can be pulled up so you can "keep others out", lol! Good luck, it sounds fun.